The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
A lithium air battery generally includes a negative electrode capable of storing and discharging lithium ions, and a positive electrode using oxygen in the air as a positive electrode active material. The positive electrode includes an oxygen evolution and reduction catalyst, and an electrolyte disposed between the negative electrode and the positive electrode. The lithium air battery has very high energy density, since oxygen in the air is used as the positive electrode active material, whereby the lithium air battery has attracted considerable attention as the next-generation battery.
When the lithium air battery is discharged, lithium generated from the negative electrode is coupled to oxygen for generating a lithium oxide in positive electrode, and the oxygen is reduced (oxygen reduction reaction: ORR) to generate oxygen negative ions. On the other hand, when the lithium air battery is charged, the lithium oxide is oxidized, and the oxygen is evolved (oxygen evolution reaction: OER) to generate oxygen.
In particular, we have discovered that the lithium oxide formed during the discharging of the lithium air battery is not sufficiently dissolved in an organic solvent, and thus exists as a solid oxide. In this case, the solid-state lithium oxide accumulates in a reaction site of the positive electrode, which is a carbon electrode, to block an oxygen channel, whereby the diffusion of oxygen is impeded. That is, the solid-state lithium oxide impedes contact between oxygen and lithium ions, and blocks pores in carbon. Accordingly, it is difficult to form a lithium oxide, whereby the capacity of the battery is reduced. In addition, some lithium oxide that have not been reduced during the charging of the battery are existed as a side-reaction deposit, which impedes the transmission of an electric charge, whereby high resistance and high voltage are caused. Accordingly, the battery may be deteriorated due to the decomposition of the electrolyte.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure, and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.